[Resolved] [Plugin: W3 Total Cache] Self CDN and thumbnails

This plugin is awesome.
I have it all working and using the self hosted CDN.(using ftp)

I have 2 web servers, 1 mysql, 1 cdn + memcache server.
This works for the most part except all the thumbnails in the admin./wp-admin/upload.php
The URI’s for the images in the admin still point to the wordpress default location – wp-content/uploads/2010/09/2010-bmw-135i-roadtestreview-01-150×150.jpg

This is an issue as we have 2 webservers and the images only appear on the one webserver.
If I look on the CDN box the image exists there but it seems the URI’s are just not being re-written.

If I visit the site the images I have upload are served from the CDN.
Is this a bug, mis-configuration on my behalf or expected behaviour ?